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vegetable oil, say linseed or rape, and mix it with one-tenth its bulk of chloride of sulphur, and slightlywarm the mixture; a strong reaction takes place,hydrochloric acid is disengaged, and a mass remainswhich, when washed with v r ater, becomes white, andis as elastic as genuine caoutchouc, with preciselythe same appearance. This curious body resists theaction of boiling alkalies; ammonia and concentratedacids are without action on it, and it resists the sol-vent powers of alcohol, ether, bisulphide of carbon,and oils.
The dichloride is produced by passing chlorineinto the monochloride whilst cooled by a freezingmixture of ice arid salt. If the temperature bereduced to —20° C. still more chlorine is absorbed,and the tetrachloride is formed.
Jotlide of Sulphur , SI 2 , is used in medicine.
SULPHURIC ACID. — Vitriolic Add—Oil of Vitriol.Acide Stdphuritjue (French ) ; Schwefelzaure . (Ger-man), II,S0 4 . A colourless, transparent, oily liquid,of specific gravity, 1-848: it freezes at — 26° C.(— 15° Fahr.), boils at 327° C. (620° Fahr.), andwhen heated passes off in colourless vapours, whichproduce a thick white cloud in contact with themixture in the air. It is inodorous, and at ordinarytemperatures it does not fume. It corrodes organicmatters very strongly, and is coloured brown by them.
Gebee, an Arab of the eighth century, obtainedsulphuric acid by distilling alum ; and Basil Valen-tine of Erfurt (born 1394) is the first to mentionits properties as extracted from green vitriol (sul-phate of iron). It w r as known also to Paracelsus ,a Swedish chemist , who died in 1541. GerardDormeat gives an account of it in 1570. Theformation of anhydrous sulphuric acid (sulphuricanhydride (S0 3 )) by the burning of sulphur wasfirst brought into notice in England in 1720. Thecomposition of the anhydrous acid was examined byRichter, Klaproth, Buciiolz, and Berzelius , andagain very carefully by Stahl, and by Sciieele in1771; by Priestley in 1774, who first collected itas a gas over mercury; in 1782 by Bertholet; andin 1797 by Fourcroy.
Sulphuric acid exists in volcanic springs. It isfound in large quantities in a torrent flowing fromthe volcano of Parce in the Andes, and Boussin-gault has calculated that this stream carried down15,000 tons of sulphuric acid yearly, and 11,000tons of muriatic acid. A stream from an activevolcano in New Granada has been found by Dagaul-iiaedt to contain even greater quantities of sulphuricacid. Roberts has found sulphuric acid in the hotsprings of the Solfatara Krisovik in Iceland . Freesulphuric acid (produced by the decomposition ofiron pyrites) has occasionally been found in the coalmines of Northumberland. It exists in both theorganic and inorganic kingdoms in combinationwith ammonium, potassium, sodium, barium, stron-tium, calcium, magnesium, aluminium, zinc, lead,copper, iron, &c.
Anhydrous Sulphuric Acid (Sulphuric oxide or anhy-dride, S0 3 .) can be produced by heating fuming oilof vitriol in a retort, the neck of which passes air-tight
into a perfectly dry receiver surrounded by ice : thesulphuric oxide distils over first, and then hydratedsulphuric acid. Sulphuric anhydride forms thinneedle-shaped crystals, arranged in feathery groups,and of a white, opaque, asbestos-like mass. It istough, and difficult to cut. Specific gravity, 1-954,and, in a liquid state, U97. It fuses at about 18° C.,and boils at 35° C. when recently prepared; butsubsequently assumes an allotropic condition, inwhich it remains solid up to 100° C., when it meltsto a colourless liquid, whilst being heated to thistemperature it volatilizes, and returns to its normalcondition.
Sulphuric anhydride may be held for a timebetween the dry fingers, but soon produces apenetrating sensation.- It hisses violently whenthrown into water, forming sulphuric acid withevolution of heat. It produces dense white fumesin the air. It is very corrosive and poisonous. Itssolution in water has a strongly acid taste, andreddens litmus paper, whereas the anhydrous sul-phuric acid does not redden dry litmus paper.When sulphuric oxide (S0 3 ) is passed through ared-hot porcelain tube, it is resolved into a mixtureof 2 volumes of sulphurous oxide (S0 2 ) and 1 volumeof oxygen (Berzelius ). Phosphorus takes fire inthe vapour of anhydrous sulphuric acid at ordinarytemperatures, and deposits sulphur in the form of athick crust (Vogel). At ordinary temperatures thevapour of sulphuric anhydride does not act uponzinc, tin, lead, iron, copper, mercury, or silver.
F, C. Vogel has discovered that sulphuric oxidecombines with sulphur in several proportions,forming a brown, green, and a blue compound, thefirst containing the most and the last the smallestquantity of sulphur. Wach prepared these sub-stances by placing washed and well-dried flowersof sulphur and anhydrous sulphuric acid in alternatelayers in a bent tube, which was sealed, and leavingthem to act upon each other at a temperaturebetween 16° and 19° C. The sulphur was firstconverted, with slight rise of temperature and evolu-tion of gas, into a thick red-brown liquid, -which, bytaking up more acid, assumed a brown, green, orblue colour. Similar colours can be observedfrequently in the strong “drops” of the ordinarysulphuric acid chamber.
Sulphuric acid (II 2 S0 4 ) is intensely acrid andcaustic; it acts rapidly upon the cuticle, occasioninga biting sensation and a soapy feel of the part, evenwhen diluted. It is extremely sour, and it powerfullyreddens litmus. It has a strong attraction for water,and in moist weather, if exposed, 3 parts increaseto 4 in twenty-four hours. This property makesit useful in drying gases and other substances.
When sulphuric acid is suddenly mixed withwater much heat is evolved, it can even be madeto boil; 4 parts of acid, specific gravity 1-8, and1 of water at 32° Fahr. (0° C.) produce, when mixed,a temperature of 212° Fahr. (100° C.) The greatestheat is evolved by mixing 73 parts of acid with 27parts of water (Ure). Even a boiling temperaturedoes not prevent sulphuric acid from taking up